Construction And Optimization Of (-)-Limonene Biosynthesis Pathways In Escherichia Coli

Limonene is an important monoterpene used as commodity chemical and precursor for producing biofuels, flavor and medicinal compounds. In this paper, we engineered Escherichia coli by embeding two exogenous genes encoding a limonene synthase (LS) and a geranyl diphosphate synthase (GPPS) for production of limonene. Out of12E. coli strains transformed with various plasmids, the best one with p15T7-ls-gpps produced limonene with a titer of4.87mg/L. In order to enhance the limonene production, two rate-limiting enzymes in the endogenous MEP pathway of E. coli,1-deoxy-xylulose-5-phosphate synthase (DXS) and isopentenyl diphosphate isomerase (IDI), were overexpressed consectively on vector pET21a+, resulting in a production of17.4mgiimonene/L at48h. After the optimization of medium in a two-phase culture system composed of n-hexadecane (1/50, Vorg/Vaq), the final production of limonene was raised up to35.8mg/L, representing approximately a7-fold improvement compared to the initial titer.